| Value | Category | 
                                    
                    
                        | 1 | 10 years or more older | 
                                    
                    
                        | 2 | Less than 10 years older | 
                                    
                    
                        | 3 | Older, Don't know difference | 
                            
            Warning: these figures indicate the number of cases found in the data file. They cannot be interpreted as summary statistics of the population of interest.